Optical transceivers are used to transmit and receive optical signals for various applications including, without limitation, internet data center, cable TV broadband, and fiber to the home (FTTH) applications. Optical transceivers provide higher speeds and bandwidth over longer distances, for example, as compared to transmission over copper cables. The desire to provide higher speeds in smaller optical transceiver modules for a lower cost has presented challenges, for example, with respect to thermal management, insertion loss, and manufacturing yield.
Optical transceiver modules generally include one or more transmitter optical subassemblies (TOSAs) for transmitting optical signals and one or more receiver optical subassemblies (ROSAs) for receiving optical signals. In general, TOSAs include one or more lasers to emit one or more channel wavelengths and associated circuitry for driving the lasers. In general, ROSAs include a demultiplexer and one or more lenses to separate received channel wavelengths and convert the same into proportional electrical signals. Some applications requiring relatively long transmission distances can include a TOSA with a thermal management device such as thermoelectric cooler (TEC) to monitor channel wavelengths and heat/cool lasers to stabilize wavelengths and mitigate drift. TECs can include Pelletier elements sandwiched between two ceramic plates/faces. Such TECs are generally designed with materials that provide a sufficient amount of thermal transfer to ensure wavelength stabilization.